"All right!" yelled Ned, as soon as he heard Tom's cry. "I've got her under control. We'll volplane down."

"Is it dangerous? Are we in danger?" asked Peter Petrofsky of his brother, in Russian.

"I guess there's no danger, where Tom Swift's concerned," was the answer. "I have not volplaned much, but it will be all right I think."

And it was, for with Ned Newton to guide the craft, while Tom did his best to stop the leak, the craft came gently to earth on the outskirts of a fairly large Siberian city. Almost instantly the Falcon was surrounded by a curious throng.

"You had better keep inside," said Ivan Petrofsky to his brother and Mr. Borious. "Descriptions of you are probably out broadcast by now, but I am still sufficiently disguised, I think."

"But what is to be done?" demanded the younger Russian brother. "If the gasolene is gone, how can we leave here?"

"Trust Tom Swift for that," was the reply. "Keep out of sight now, there is a large crowd outside."

Tom came from the tank room. There was a despondent look on his face.

"It's all gone--every drop," he said. "That's what made the motor stop."

"What's gone?" asked Mr. Damon.

"The gasolene. We sprung a leak in the main tank, somehow, and it all flowed out while we were flying along."

"Haven't you any more?"

"Not a bit. I was drawing on the reserve tank, hoping to get to civilization before I needed more. But its too late now. We will have to--"

"Bless my snow shoes!" cried Mr. Damon. "Don't say we'll have to stay here--in Siberia! Don't say that. My wife--"

"No, we won't have to stay here if we can get a supply of kerosene," interrupted Tom. "The motor will burn that. The only trouble is that we may be detained. The authorities probably know us by this time, and are on the watch."

"Then get it before they know we are here," advised Ned.

"I'll try," said Tom, and he at once conferred with the elder Petrofsky. The latter said he was sure kerosene could be had in town, and, rather than risk going in themselves, they hired a wagoner who agreed, for liberal pay, to go and return with a quantity. Until then there was nothing to do but wait.

Meanwhile the crowd of curiosity seekers grew. They thronged around the airship, some of them meddling with various devices, until Tom had to order them away with gestures.

One particularly inquisitive man insisted on pulling or twisting everything, until he happened to touch a couple of live wires, giving himself quite a shock, and then he ran away howling. But still the crowd increased, and at last Mr. Petrofsky said:

"I don't like this, Tom?"

"Why not?" They were all inside the craft, looking out and waiting for the return of the man with the kerosene. The leak in the tank had proved to be a small one, and had quickly been soldered. It had been open a long time, which accounted for the large amount of gasolene escaping. "What don't you like, Mr. Petrofsky?"

"So many men surrounding us. I believe some of them are officers dressed in civilians' clothes, and a Russian officer never does that unless he has some object."

"And you think the object is--?"

"To capture us."

"If it was that, wouldn't they have done it long ago--when we first came down?"

"No, they are evidently waiting for something perhaps for some high official, without whose orders they dare do nothing. Russia is overrun with officialdom."

And a little later Ivan Petrofsky's suspicion proved true. There arrived a man in uniform, who spoke fairly good English, and who politely asked Tom if he would not delay the start of the airship, again, until the governor could arrive from his country place to see it.

"We know you are going to leave us," said the Russian with a smile, "for you have sent for kerosene. But please wait."

"If your governor comes soon we'll wait," replied Tom. "But we are in a hurry. I wish that kerosene fellow would get a move on," he murmured.

"Oh, he will doubtless be here soon," said the officer. "Might I be permitted to come aboard and wait for my chief?"

"Sorry, but it's not allowed," replied our hero, straining his eyes down the road for a sight of the wagoner. At last he came, and Tom breathed easier.

But the crowd was bigger, and some of the men, though poorly dressed, seemed to be persons in authority. Tom had no doubt but what there was a plot afoot to detain him, and arrest the exiles, and that there were disguised soldiers in the throng. But they could not act without the governor's orders, and he was probably on his way with all haste.

"Lively now, get that kerosene in the tanks!" cried Tom to the man, motioning in lieu of using Russian. The youth was not going to meet the governor if he could help it.

Now it was a curious thing, but the more that wagoner and his helpers seemed to try to hurry, and pour the oil from the cans into the tank-opening of the airship, the slower they worked. They got in each others' way, dropped some cans, spilled others, and in general made such poor work at it that Tom saw there was something in the wind.

"Ned!" he exclaimed, "they're doing all they can to detain us. We've got to put that oil in ourselves. Just as we did the gasolene in France. It's the same sort of a delay game."

"Right, Tom! I'm with you."

"And I'll warn the crowd back, by telling them we are likely to blow up any minute!" added Ivan Petrofsky, which warning he shouted in Russian a moment later.

Backward leaped the throng, as though a bomb bad been thrown into their midst, even the supposed officers joining in the retreat. The oil wagon was now easy of access, and Tom and Ned, with Mr. Damon to aid them, hastened toward it. Then the work of filling the tanks went on in something like good old, United States fashion.

The last gallon of kerosene had been put aboard, and Tom and Ned with Mr. Damon, had climbed on deck, when the gaily uniformed officer, who had requested the delay, came riding up furiously.

"Hold! Hold! If you please!" he cried. "The governor has come. He wants to see you."

"Too late!" answered Tom. "Give him our best regards and ask him to some to the United States if he wants to see us. Sorry we haven't cards handy. Ned, take the pilot house, and shoot her up sharp when you get the signal. I'm going to run the motor. I don't know just how she'll behave on the kerosene."

"You must remain!" angrily cried the officer.

"The United States doesn't take 'must' from anybody, from the Czar down!" cried Tom as he disappeared into the motor room. The window was open, and the youth turned on the power the official cried again to him:

"Halt! Here comes the governor! I declared you arrested by his orders, and in the name of the Czar!"

"Nothing doing!" yelled Tom, and then, looking from the window, he saw approaching a troop of Cossacks, in the midst of whom rode a man in a brilliant uniform--evidently the governor.

"Stop! Stop!" cried the official.

"Here we go, Ned!" yelled Tom, and turning on more power the Falcon arose swiftly, before the very eyes of the angry governor, and his staff of Cossack soldiers.

Up and up she went, faster and faster, the motors working well on the kerosene. Higher and higher. The governor and his soldiers were directly below her now.

"Stop! Stop! You must stop. The Imperial governor orders it!" yelled the officer, evidently his Excellency's aide-de- camp.

"We can't hear you!" shouted Tom, waving his hand from the motor room window, and then, turning on still more power he flew over the city, taking his friends and the valuable supply of platinum with him. So surprised were the soldiers that they did not fire a shot, but had they done so it is doubtful if much damage could have been done.

"And now for home!" cried Tom, and homeward hound the Falcon was after a perilous trip through two storms. But she weathered them well.

In due season they reached Paris again, and now, having no reason for concealment, they flew boldly down, to change what remained of the kerosene for gasolene, as the motor worked better on that. The secret police learned that the exiles were aboard, but they could do nothing, as the offenses were political ones, and so Tom kept his friends safe.

Then they started on the long voyage across the Atlantic, and though they had one bad experience in a storm over that mighty ocean, they got safely home to Shopton in due season.

There is little more to tell. The platinum proved to be even more valuable than Tom had expected. He could have sold it all for a large sum, but he preferred to keep most of what he had for his inventive work, and he used considerable of it in his machinery. Ned disposed of his, selling Tom some at a lower price than market quotations, and the Russians got a good price for theirs, turning the money into the fund to help their fellow exiles. Mr. Damon also made a good donation to the cause, as did Tom and Ned.

Mr. Petrofsky and his brother, with the other exile, joined friends in New York, and promised to come and see Tom when they could.

"Well, I suppose you'll take a long vacation now," said Mary Nestor, to Tom, when he called on her one evening to present her a unique ring, with the stones set in some of the platinum he had dug in the Siberian mine.

"Vacation? I have no time for vacations!" said the young inventor. "I'm soon going to work on my silent airship, and on some other things I have in mind. I want more adventures."

"Oh, you greedy boy!" exclaimed Mary with a laugh.

And what adventures Tom had next will be found in the next book of this series, which will be entitled, "Tom Swift in Captivity; Or, a Daring Escape by Airship."

Tom had several offers to give exhibitions in his air glider, from aviation committees at various meets, but he declined.

"I haven't time," he declared. "I'm too busy."

"You ought to rest," his chum Ned advised him.

"'Bless my alarm clock!' as Mr. Damon would say," exclaimed Tom. "The best rest is new work," and then he began sketching his ideas for a silent motor craft, during which we will take leave of him for a while.